The present invention relates generally to orthotic inserts for use in conjunction with various types of footwear.
The following patent application deals with developments concerning applicant's own U.S. Pat. No. 3,995,002 issued Nov. 30, 1976, U.S. Pat. No. 4,237,626 issued Dec. 9, 1980 and application Ser. No. 294,306 filed Aug. 19, 1981.
The first citation teaches the use of an orthotic casting system whereby a slipper mold is taken of the plantar surface of an individual's foot which, when the mold is cured, provides a negative template from which a positive cast can be fabricated. The final insert is then constructed using the positive cast to emulate the plantar surface of the individual's foot.
The second of applicant's patents cited teaches the use of a heel cup insert which is deformable and which can take an impression of the plantar surface of the heel and maintain that contour when cured so that the angulation of the calcaneal area can be adjusted to correct for rear foot varus or valgus.
The application cited provides a significant time saving in the ortho-casting process because it eliminates the necessity of making a negative mold from which the positive insert is constructed. Instead, the original mold itself becomes the insert. By eliminating a time consuming and labor intensive step custom fit orthosis can be created quickly and at a reduced cost.
The instant application represents a significant and novel improvement over the art disclosed in the above citations. Although a process may be somewhat the same as that described in applicant's U.S. Pat. No. 3,995,002, the materials employed in the instant application exhibit certain synergistic characteristics that further enhance desirable effects in a new, novel and unobvious manner.
The structure disclosed herein employs the ortho-casting method in applicant's U.S. Pat. No. 3,995,002 to form a negative mold or slipper cast from which a positive cast of the plantar surface of an individual's foot is formed. Using this positive cast as a template, an orthotic insert is formed to underlie the area under the foot from the calcaneal area forward to the first metatarsal head, including the arch area, and from there laterally to the distal side of the foot or fifth metatarsal head. The insert itself is fabricated by applying to the positive cast a fiberglass and resin wafer selectively impregnated between layers having graphite fibers. The insert is then heat cured and cut to the limits of the cast. This is significant because of the unexpected benefits associated with the resulting structure due to the order and direction in which they are laminated together. The flexing characteristics of the insert, which are integral to its performance, can be beneficially controlled by adjusting the placement, amount, and direction of the graphite fibers impregnated between the layers of resin and fibre glass. The insert formed using the structure disclosed herein is extremely lightweight and relatively thin in comparison and is even more tuneable to the person's foot and activities because flex and rigidity can be adjusted over different areas of the insert to emphasize certain orthotic needs and compensate for certain orthotic abnormalities. If orthotic adjustment is painful to the patient because of excessive rigidity in a particular portion of that orthotic then it can be initiated gradually by introducing a further insert with a preferred zone of accentuated flexibility in the appropriate area, while maintaining a preferred rigidity throughout the remainder of the insert. This is accomplished by varying the configuration of the impregnated graphite and the thickness of the resinous core.